Question

In a shunt-wound dc motor with the field coils and rotor
connected in parallel (see the figure (Figure 1) ), the resistance
R_f of the field coils is R_f = 102 Omega and the resistance R_r of
the rotor is R_r = 5.7 Omega . When a potential difference of V = 1
V is applied to the brushes and the motor is running at full speed
delivering mechanical power, the current supplied to it is 4.8
A.